Sharpness at such speeds is entirely subjective. Given the kind of use cases this lens will most likely be used for (birds, wildlife and other action with cropped sensor cameras), at 1/40s, your likely going to get considerable blur, even if you have steady hands. Your subjects will be moving, and even a small amount of movement (ESPECIALLY for birds) at anything under about 1/800s results in blur.

I used to try to keep my shutter speed slower with the 7D to keep noise levels lower (and avoid having to go over ISO 1600), however for passerines, they are so jittery and constantly on the move that anything under about 1/800s (and in the case of the really small, super hyper birds like chickadees or bushtits and the like, even shutter speeds of 1/1250s and slower) results in subject blur. This was even the case with the EF 600mm f/4 II on a heavy duty tripod and gimbal (GT3532LS + Jobu Pro 2).

The only time your going to get stable 1/40s shots hand-held is if there is no motion in the scene. I had the luck of getting a 1/6s handheld shot ONCE in my entire time photographing:

The only reason I was able to get the shot is because the bird was literally motionless for the entire time it took me to uncap the lens, stabilize myself so that I was motionless, configure the right camera settings, and take the shot. This was about a half hour or so after sunset, during the last minutes of civil twilight/first minutes of astronomical twilight. It was truly "night". Unless you intend to go around photographing night herons at night, I don't expect many nature photographers who get the Tammy 150-600 will be getting many sharp handheld shots at such low shutter speeds.

BTW, I used zone AF in my 5D3 with the central group. AF was set to Case 3: focus on subject entering the focus area. This is because I find it often difficult to keep a flying bird on the active AF area. However, I suspect that my movement trying to follow the bird caused some loss of sharpness. Shots at 1/2000s look better than those at 1/1000 but still not tack sharp in any point - i.e. it doesn't seem the focus is off.

Thanks Jon, I am sure you are right. The heavy cropping we do with birds is stretching the camera to its limits and we need much higher speeds than indicated by the old rule and the number of IS stops. Further, I think I have read that the old rule of thumb that you need a shutter speed of faster than 1/f breaks down at as f increases and so a 600mm requires more than 1.5x the speed at 400mm. The 1.6x crop factor on the 7 or 70D comes into it as well, and again more than 1.6x.

well that doesn´t mean it has to be the lens or VC. exactly what i meant. are you able to hold a different (canon) 600mm lens at that speed?

i know people who can handle 600mm with IS at 1/30s or 1/40s but im not one of them.as im not one of the guys who can shoot a 600mm handheld without IS at 1/600s.

you can´t just say "the rule is 1/focal length and this is a 4 stop VC so i should be able to hold it at 1/40s". that´s taking YOU out of the equation.

when you look at professionell bird photographer most of them use a tripod or at least a monopod.for a good reason.

next thing i will buy is a gimbal.

Here is a recent quote from Art Morris, one of the most famous professionals of all time:

"2) The Sharp, Fast, Versatile 300mm ƒ/2.8For years I had my eyes and my mind closed to the 300mm ƒ/2.8 lenses. That all changed when I borrowed one for my big Antarctica trip with Cheesemans' Ecology Safaris in early 2012. I loved it so much that I extended the loan and brought it along to Japan for a month. On the Southern Oceans trip, I needed to travel light; the Canon 300mm ƒ/2.8L IS lens was my big lens. It was great in the Zodiacs® and great for handheld birds-in-flight photography with or without the 1.4x TC. I used it with the 1.4x TC for all of my sea eagle flight photography in Hokkaido, and it was great for the snow monkeys as well. Aside from the light-gathering ƒ/2.8 speed, the lens is mind-bogglingly sharp. Canon EOS-1D Mark IV, EF 300mm ƒ/2.8L IS USM, Extender EF 1.4x III, handheld "

Professionals use tripods or hand hold according to circumstances. The 400/5.6 was (and still ) is so popular because hand holding is necessary for much bird in flight photography. Now, we can use the Tammy or 300/2.8 - we are so lucky.

Thanks to a tip from Roo, I picked up this lens on Friday.First serious tests this evening and so far it's looking pretty good (IMO) - will take a bit of practice though, keeper rate is a bit low

Phil.

Hi Phil, I really like your #2!

Have have you been finding the AF on flying birds?

Thanks.

I struggle to keep any flying birds in the viewfinder, let alone within the cameras AF area, so it's hard to make any real comment on the lens AF. When I did manage to follow a bird the lens AF seemed to work ok.

Tried out the Black Rapid RS-4 this afternoon. The Tammy is very comfortable hanging from it. As some might know, my 5DIII once fell off the 300mm when it was slung over my shoulder. I'd like to secure the 5DIII to the Black Rapid and also have an extra safety link from the Tammy/camera to the shoulder strap in case the screw comes loose from the Tammy tripod bush. I am thinking now of getting the Black Rapid wrist strap, screwing that into the 5DIII and threading its loop through the shoulder strap that is attached to the lens tripod mount. Has anyone tried something like this or has a better suggestion?

Sorry for the tardy reply, AlanF, but this is the first chance I've had to take photos of my strap set-up. I haven't yet dropped a lens or body, but I came close to dropping my 5D one time when changing lenses from my shoulder strap. So, like you, I prefer a fail-safe.

I prefer the Joby strap to Black Rapid. I like their rubber bushing/style of lock-nut better and I can adjust the length of their strap very quickly with one hand/no buckles. That means I can wear it long enough to hold my camera/lens beside my waist, gun-slinger style for quick action, then quickly suck it up under my arm pit if I want to scramble up a rock without banging the camera into everything.

Both body and lenses-with-collars are equipped with Induro PU-60 base plates for my tripods.

I attach the Joby slider to a Kirk 1" Std Quick Release which attaches to either the camera, for short lenses, or collars, for long lenses. This allows me to quickly doff the strap and attach either the body or lens to my tripod in a heartbeat. I got the idea to use the Kirk SQR from Neuro, and it hasn't let me down yet.

Next, I use an Optek neoprene wrist leash (very soft and comfortable) on my right wrist, making sure to tighten up the toggle. It stays on my wrist all day. I modified the tip of the leash by sewing on a 5/8-inch, male-side, Fastex Side-Release buckle. I then sewed a very short female Fastex buckle to the right-hand strap bracket on the 5D body, using a short length of webbing. Make sure any leash attached to the camera body itself--chest strap or wrist strap--is as short as possible to minimize wind flappage.

This set-up allows me to have both my lens and camera attached to me at all times, together and/or independently. The wrist leash is long enough that I can still get into my backpack, take a drink of water, etc., without unclipping myself from the camera body, as the whole rig hangs at my side from the chest strap. If I want to change lenses while all leashed up? No problem. Lenses with or without a collar? No problem. Quickly jump to a tripod regardless of lens? No problem.

This is the most versatile set-up I've come up with. I don't like hand straps--something you were leaning towards--because they often use up the body's tripod mounting threads where I'd prefer to have a base plate. Too, though they offer some added stability, they're too slow to get in and out of as circumstances change. Finally, you can see in the photos that I keep my collars rotated 90-degrees when dangling the camera/lens from my Joby so I can quickly lift the body by its grip and rest the barrel of the lens on my left hand. Obviously, I have to loosen the collar screw and rotate things right-side up when jumping to a tripod. I find this 90-degree collar tilt also puts the body/lens in the best gun-slinger position for a quick-response shot.